- Peshastin is a small unincorporated community in Chelan County, Washington, United States. The community’s roots are found in the “Peshastin Ditch” dug by pioneers beginning in 1889. This ditch was an important part of the overall irrigation system in the area, delivering water to the orchards on the slopes above Cashmere. The town was first platted in the early 1890s by two brothers, J. Q. Gilbert and A. C. Gilbert. It is also noted on an 1895 map of the area, indicating it was in existence by then.